myapp.java

Java的面向对象数据库系统的源代码

import org.ozoneDB.*;

public class MyApp {
    
    private static ExternalDatabase	db;

    public static void main( String[] args ) throws Exception {

        if (args.length == 0) {
            System.out.println( "usage: ojvm MyApp create|delete|print" );
            System.exit( 1 );
        }
        
        // create and open a new database connection
        db = ExternalDatabase.openDatabase( "ozonedb:remote://localhost:3333" );
        System.out.println( "Connected ..." );
        
        db.reloadClasses();
        
        if (args[0].equals( "create" )) {
            createCar();
        } else if (args[0].equals( "delete" )) {
            deleteCar();
        } else {
            printCar();
        }
        
        db.close();
    }

    public static void createCar() throws Exception {
        // create a new Car object with the name "my_first_car"
        // the return value is Car_proxy, which implements the Car-interface
        Car car = (Car)(db.createObject( CarImpl.class.getName(), 0,
                "my_first_car" ));
        
        car.setName( "gottfried" );
        car.setYearOfConst( 1957 );
    }

    public static void printCar() throws Exception {
        Car car = (Car)(db.objectForName( "my_first_car" ));
        if (car != null) {
            System.out.println( "The car " + car.name() + " is " 
                    + car.age() + " years old." );
        } else {
            System.out.println( "Object my_first_car not found." );
        }
    }
    
    public static void deleteCar() throws Exception {
        Car car = (Car)(db.objectForName( "my_first_car" ));
        if (car != null) {
            db.deleteObject( car );
        } else {
            System.out.println( "Object my_first_car not found." );
        }
    }
}